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Old 12th June 2007, 04:35 PM   #1
ReTrO is offline ReTrO  England
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Default Dual 12" Subwoofer Project

I've started up a project to make a pair of subs based on the Audio Drive 12-300SB 12" driver (a modified Eminence LAB12, used by BK Electronics in their Monolith sub).

It's going to run each drive in independant enclosures, of a compact size as possible (room size is a big restriction currently), sealed with an off-board power amp. I currently have a Behringer BFD for room EQ, though am also likely to use a Linkwitz Transform circuit to bring up the bottom end.

I've started a thread over on the AVTalk forum, but will post on here too.

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The one issue I have encountered so far is that when I input the speaker parameters into WinISD Pro it disagrees with the Cms info.

Listed as 0.35mm/N by Audio Drive, but WinISD gives me 0.1977mm/N.

Specs:

Impedance: 4ohms
Power: 300W
SPL 1W/1M: 86dB
Fs: 23.5hz
Re: 3.7ohms
Le: 1.30 mH
Qms: 2.73
Qes: 0.416
Qts: 0.361
Vas: 61.6 Litres
Mms: 232g
Cms: 0.35mm/N
BL: 17.46 T/M
Sd: 468.7 cm2
Xmax: +/-7.5mm

I don't have any easy way of measuring the info myself.
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Old 13th June 2007, 01:47 PM   #2
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A few design images, for those who like that sort of thing; like me!

My old RTP-15 sub and the correctly scaled new design (one of).

Click the image to open in full size.


The pair next to each other.

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The pair stacked, for use in my current small room.

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Old 14th June 2007, 09:39 AM   #3
ReTrO is offline ReTrO  England
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On checking with BK it would appear that the 0.35mm/N is a data entry error and the 0.1977mm/N should be used.

Many thanks to Baz for being prompt with his reply.
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Old 17th June 2007, 12:57 PM   #4
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2 sealed will be nice, I look forward to the results.

These really do gain from porting, dual Monolith anyone? 5.5-6.5 cubes tuned to 20hz would be fantastic!
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Old 17th June 2007, 01:03 PM   #5
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I would also use a vented box.
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Old 17th June 2007, 01:04 PM   #6
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If I had the room to house them I'd probably go down the ported route.

As it is I'm currently sorting out small deatils, connectors etc to use, and getting a cost to have the cabinet parts cut properly. If I did them myself it would probbaly cost just as much, and also ages of time, to get the spare materials and tooling.

Should be fun. I'm needing to do some cabinet finish tests soon.
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Old 17th June 2007, 01:41 PM   #7
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My only concern with side firing the drivers is that the cabinets may 'walk'. Otherwise looks like a nice project. I can put you in touch with a company that can cut and router the panels if you want.
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Old 17th June 2007, 01:53 PM   #8
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Quote:
Originally posted by richie00boy
My only concern with side firing the drivers is that the cabinets may 'walk'. Otherwise looks like a nice project. I can put you in touch with a company that can cut and router the panels if you want.
Most of the time well contructed solid enclosures don't do this.

Some tips! If they do move then a square or cross of velcrow will stop this on carpet.

If on wood or slippy surface like tile then rubber strips or weather stripping or some cured silicone sealed ridges will stop it.

There always a solution.
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Old 17th June 2007, 02:34 PM   #9
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The cabinet will have decent feet of some sort to ensure they stay put. The current surface they have to contend with is carpet, and it is likely to stay that way when I move house, so pobably some good spikes for now.

I've not had any issues with walking cabinets on sub projects, as they're pretty heavy, well braced enclosures, normally ending up on spikes for the carpet. The upper of the 2 when stacked with gain some 'rubber feet', not sure exactly what yet.


richie00boy, if you could email me the company/contact that would be much appreciated.
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Old 17th June 2007, 02:40 PM   #10
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Some more recent pics (these are on the AVTalk forum already).

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